Investigations of the effect of (Cr1 −x, Al x)N coatings’ micro Structure on Impact Toughness

Originated from the tooling industry, PVD (Physical Vapor Deposition) coating development focused on increasing the wear resistance. Nowadays, a steadily increasing market is evolving by coating machine parts. The requirements that have to be met due to the needs of this new market segment focus on tribological behavior. This means, that the focus of wear resistance is shifted towards properties like coefficient of friction, wetting behavior and the response of coatings towards dynamic loads. For many tribological applications, coatings are exposed to severe alternating loads, which are usually left out in common test methods. The approach of common coating test methods are based on the static behavior of deposited coatings. The impact tester is a testing device with a novel approach to dynamic load behavior of both bulk and coated materials. In this paper, the effect of the coatings' microstructure and Young's modulus on the impact toughness was investigated. A change in microstructure was provoked by changing deposition parameters like aluminum content. In a second stage these coatings were then tested with respect to their response to high alternating loads. For this purpose both load and number of impacts were varied.